The Mental Retardation Research Center (MRRC) of the University of California, Los Angeles conducts research on mental retardation and related aspects of human development, using a variety of disciplinary approaches. These range from anthropological studies of mentally retarded persons to molecular aspects of inherited metabolic diseases. Our research is characterized by strong interactive efforts in which scientists from different disciplines attack problems of common interest. In addition to our research mission, the MRRC is active as a teaching unit, particularly in our research training activity for graduate students and postdoctoral trainees. This application is a request for funding for the acquisition of the computer system required by the continuing growth of the research programs of the MRRC. Currently, our research is supported by four PDP-11 computers, a variety of micro-processors and remote job entry to UCLA campus computing facilities. These arrangements are inadequate. They do not permit use of the latest computational methods available to us. The genetics and neurophysiology projects are at a technological standstill. It is essential that we obtain significantly increased computing power soon. Central facilities are very costly, and no single research project can afford to purchase a sufficiently large computer. The core support grant has been severely restricted by level funding during a period of rapidly increasing costs. Space is availabale and maintenance would be provided by UCLA. An experienced staff of programmers and statisticians are available to develop and use the new system. Several of the most promising research projects are hampered by serious limitations on computing resources; alternative approaches are more expensive or technologically complex. What we need is an adequate computer, as requested by this proposal.